1. Field of the Invention
This invention relates to a pneumatic tool such as a nailing machine having an air chamber for storing compressed air.
2. Description of the Prior Art
In general, a pneumatic tool includes an air chamber for storing compressed air which is used as a power source. The air chamber is detachably connected with a hose from a compressed air source through a joint which is mounted to an inlet port of the air chamber. The hose is frequently connected with or disconnected from the joint for exchange of the tool. Such frequent connecting and disconnecting operations may possibly cause entry of dust into the air chamber through the joint. The dust may further enter a trigger valve, a head valve, a percussion cylinder, etc. in the tool and particularly cause deterioration of seal members such as O-rings or cause flaws on the sealing surface of them, thereby causing insufficient sealing.
To prevent entry of dust, it has been proposed to provide a filter in the joint for capturing the dust.
The joint, however, has small flow area and the filter must have small size. Therefore, the filter may prevent flow of air causing insufficient amount of flow if it has fine mesh. On the other hand, the filter may not capture fine dust if it has coarse mesh.
Japanese Laid-Open Utility Model Publication No. 57-202676 discloses a cap covering a joint for preventing entry of dust when a tool is not used. The cap can be removed from the joint for connection of the joint with a compressed air source.
However, the cap requires cumbersome operation for engaging and disengaging the same. Further, it cannot prevent entry of the dust which exists in the hose for connection with the joint or the dust including the rust produced in the compressed air source such as an air compressor.